I figured I'd just ask this question even though I know what the majority answer will be.

While commuting, do you use a backpack, messenger bag, panniers?

What are your thoughts on a rear rack and or front rack i.e. porter style rack?

backpack

I don't sweat that much, have a bad shoulder and find it much easier to deal with off the bike than pannier(s).

A rando style bag would be nice for certain things, but so spendy to do it right, and the geometry of the bike comes into play.

I always use a small backpack or a" roll top" messenger bag... However I also have two bikes set up with a front wald basket and one bike with a front rack and small panniers. All of my personal belongings such as clothing , spare tubes ,tools, pump etc I carry on person in a backpack..When I go do my shopping or carry heavy bulky items I always put them in my baskets or front rack/panniers. I don't use rear racks panniers as I don't like lot's of weight on the rear, I prefer to have it on the front/

I ride with backpack strapped to rear rack with bungee net. This way I can relocate the backpack to my back if I need to stop by whatever store/farmer's market, you name it. Most of the time it stays on the rack. of course.

I use two bags that attach to the rear rack on the bike. Since they are single bags it is easy to take one or the other depending on what is needed.

Rear rack and a rack bag. A small bag forces you to limit the crap you carry and gives you an excuse for not taking work home.

Rack and Panniers. I generally have to take a lot of crap (clothes books, papers etc). I sweat like a pig and I cannot stand to have anything on my back unless I am going a very short distance.

Good point!

95% of the time I use a rear rack and one commuter pannier on my commuter bike. If for some reason I commute on one of my other bikes (road bike, fat bike) I use my old timbuk 2 messenger bag. But I far prefer to not have the weight on my body.

I prefer racks and panniers. One thing to consider is a pannier that converts into a back pack... I have the one Ortliebs makes. Overall I like it, but the connection system isn't my favorite.

I like backpacks because they are easy. They create shoulder pain on long rides though.
I like panniers because I can ride without sweat or extra body weight. But they change handling A LOT so it takes a while to get used to.
Still undecided as to what to stick with.

Backpack. I've done backpack and pannier, but the rear rack makes the bike fit in less cars when I beg a ride from someone, so it had to go.

When I ride the folder I have a rack trunk on the back rack, large enough for clothes and lunch, so that works.

When I ride the road bike, I use a backpack (kind of small one) and that works out well since my road bike will not easily accept a rack (no eyelets and carbon seatpost).

Rick / OCRR

Rear seatpost rack with trunk bag that has the fold-out panniers.

I have a front rack and panniers on the bike I ride most, a Bike Friday,
small wheel so I can carry stuff on top of the filled Panniers

the touring panniers, all 4, when I do a grocery store stop The Koga Trekking bike.

Brompton , working on a bigger ledge, on the bottom-front, of my Steel Bag support.
to make a way to carry wierd stuff.

Or Touring Bag with the current Nylon/ aluminum tube bag frame..

Backpack, hands down. The reason I choose to use a backpack rather than panniers is that I never know where I might find myself going (on-road or off-road) and I prefer to not have anything hanging off my bike so that I can maneuver more freely if I decide to take a more scenic route home. This has converted several friends to ditching their panniers as well as they found them to really be a PITA when we ride through tight traffic situations or divert to a tight trail ride, because their bikes handle a fast pace over bumpy country roads or through heavy traffic much better. If all you are going to do is pedal around on smooth surface streets by all means use panniers, but if you may find yourself riding more aggressively or over more mixed terrian, a backpack is the way to go.

My personal favorite for the past several years has been The North Face Bandwidth backpack, and I wear it almost everywhere I ride, hike, or climb.

I use a Carradice Pendle bag. That way, no added weight from a rear rack.
The Carradice Camper is a huge option, too, if you need more room.

80% of the time I take a small backpack (REI Flash 18). 10% of the time I take the old MTB with grocery bag panniers that lets me carry loads of stuff. And 10% of the time I'm lucky enough to just ride with nothing.

I care about the health of my neck, shoulders, and back. Those areas become tight if using a backpack. Panniers are the best for me!

Messenger for me, the key is a light load. MacBook Air and a lunch, that's it. I don't even carry the charging cord, I have two and one stays at work.

Funny you should ask. I just bought a set of panniers. Most of the time I ride with a small trunk bag on my rear rack and wear a backpack during the winter when I need to carry extra ride clothing. The backpack was never really a problem because I rarely had anything heavy in there and it didn't make me sweat too much. However, I just started taking a night class and it was no fun carrying books in the backpack. After all these years of commuting I'm finally going to give panniers a try.

I use a simple tote bag that I made myself. It usually rides in a cheapo basket hooked onto my handlebars. If I need the basket space for other things, I just ride with the bag on my shoulder. I've tried using a messenger bag, but didn't like it. Also, it didn't fit in my basket, so I ditched it. I know that racks and panniers can be very useful, but I don't want all that stuff on my bike. Both it and I are heavy enough as it is. My setup forces me to streamline.

Backpack, but it's going to be too hot in summer. Looking for something I can clip or bungee to my seatpost rack. Maybe I'll spring for a real trunk bag or some kind of hard trunk.

Agreed, for once. I've ditched my panniers lately in favor of a well fitted daypack for this reason.

A big backpack so I can carry 1 or more six packs home or a 15lb bag of dog food.