It took me years to start doing this. Apply lube, leave overnight then wipe off excess in the morning. Less grime sticks to the chain so it stay clean longer.

You'll need to find out what the gearing is on both bikes and make a decision based on that. The 20 spd will most likely have redundant gearing or at least some that are close enough that there's only something like a 5 rpm cadence difference at a given speed and then also factor in that in order to go through the gearing sequentially means you'll sometimes have to shift both derailleurs to get to the next step up. IMHO if you're not riding in a paceline or racing then minute differences in gearing to keep you in your optimal cadence range isn't really all that beneficial.

when it comes to gearing there seems to be more preferences than cyclists

here are some of mine. i am among the fastest on a commute and on mtb, middle of the road in a peleton.

-maximum gearing over 115 does not increase my top speed, it just lowers the cadency
-when going distances half an hour or more there is little need for gearing over 100, but i like them anyway
-if gears are spread and few, having at least one 90-95 is beneficial, it is a workhorse for going as fast as i can on flatland with no wind
-if more than a few gears are available it is preferable that there should be no more than 15% between gears 70-95 no more than 10% between gears over 95
-to get up normal hills, around 45 is almost always enough, for really steep hills there is little use for gears under 25 except for alps or on mtb
-if cogs 11 and under get any substantial use they wear themselves and the chain out in short time
-if i go really fast on a 12-cog, and gear 'up' to 11-cog speed does not increase, increasing the cadency is more efficient

so to conclude, for road or commute use total number of gears can really be limited more than what is commonplace today. the chainwheel should be big enough so that 11 and smaller cogs can be avoided, to reach a top gear of absolutely not lower than 90. gearing over 70 should preferably be tight, and in addition to that one or two climbing gears are needed. more than say 5-6 strategic gears along that line is luxury. you might want that luxury, but if will not make you noticeably faster.

for an example of minimalism, on my 2sp 9.9 kg brompton with 70 and 95 gear inches i have no problems cruising along for an hour or two in 30+kmh peletons. hills up to a limit work fine with good knees and spd pedals, but i would recommend to anyone else to get one or two climbing gears.

ergonomics of the bike is also essential, that the bike is lighter than say 14 kg is absolutely important, less than 12 kg/ 26 lbs very handy, less than 10 kg/22 lbs not that important; and above all other factors, get supple and light-rolling tires. there you go!

This bike weighs just 23# and that is with a rack and fenders, uses standard 406 20" tires, plus has a wide range 9 speed drivetrain. Oh, and it's affordable too.

not the prettiest design, but if its well put together it has a lot going for it. you might wish to tweak it with a slightly larger chainwheel and foldable or maybe detachable pedals, just minor issues.

its light, and it folds in the right direction to protect the chain and derailleur. that i really like