The bike I’m looking into has the SRAM SX Eagle drivetrain except for the rear derailleur which is a SRAM NX. Anyways I’m a Shimano fan so I need some insight on SRAM.

It is the bottom end of SRAM but it is nicer than the bottom end of Shimano sort of Alivio/Deore equivalent. People don't love it but it over all isn't so bad and assuming 12 speed is upgradable easily.

My older MTB has SRAM X7 had no problems a bit clunky. Even has a 3 chainring crank lol. Time to modernized or fall for the latest stuff.

You will probably enjoy it, it isn't that bad from what I have seen and if you really dislike it plenty of stuff to upgrade to.

I think the NX derailleur will be alright...worst comes to worst, it's pretty easy(and affordable) to upgrade the derailleur and shifter to GX in the future. IMO, GX is the happy spot in the line up that gets most of the performance and durability of the higher end group sets, but at a very affordable price.

It may not be an issue for you, but the SX cassette will be on the HG driver...meaning an 11-50 cassette. The GX and above gets you the "Eagle" with either the 10-50 or 10-52 cassette.

Big bonus about the HG driver is it give you lots of good cheap options if you hate sram to swap too down the road. An upgrade to GX shifter and RD later as stated gets you to the sweet spot but Shimano 5100 deore 11 speed or cues or microshift advent x are all inexpensive swaps. I wouldn't turn down a bike based on the drivetrain. The all pretty much work fine these days.

I will say shop suspension first and the drivetrain is not as important. My thresholds for "good" is that the fork lowers and stanchions are all made from aluminum, and oil is squeezed past shims instead of thru holes. This does cover pretty much all of Fox. This also covers anything from smaller brands like Cane Creek or MRP. For Rock Shox this puts you in the Charger damper regime and not anything named Gold or Silver or Motion Control. Suntour does have forks like this but you hardly ever see them. If it's full suspension then anything with a good enough fork will also have a good enough, probably matching shock, and a good drivetrain and brakes.

That out of the way, I don't think anyone really loves SX. It works ok. The weight of it is something else, with the heaviest cassette there ever was, and the huge steel crank spindle. I personally really dislike SRAM shifter ergonomics but you can sub in a Rapid Fire. But all that weight enables "real" mountain bike durability and features at a very low price

I just bought a gravel bike with Eagle SX cassette and the HG driver ( didnt know it was an HG). that cassette is a tank! but the main issue is if you want to upgrade to Eagle GX and higher you need to buy an XD driver to mount those cassettes. that is what I did. so another $70-90US. I have X01 and XX1 on my MTBs. a huge difference in shifting smoothness.

I have GX AXS and I am currently running an NX cassette and it works fine. I wanted HG because I like HG and I don't like anything smaller than an 11t so it doesn't wear out as quickly.

My Creo 2 came with an Eagle APEX groupset. I am slowly replacing a few bits. I already have a X01 cassette to put on, only have to swap hub driver to XD (from HG)
The SRAM Eagle cassettes of 2024/2025
SX: 720g [SRAM PG-1210 Apex 11-50t, stock on Creo 2 Comp]
NX: 615g (105g, 0.23lb lighter
GX: 451g (269g 0.6lb lighter)
X01: 372g (348g, 0.77lb lighter)

Is SRAM Eagle Apex groupset equivalent to GX?
The A.I.Team says… SRAM Apex and GX Eagle AXS groupsets are not directly equivalent, but the Apex groupset utilizes GX Eagle AXS components in its build, particularly the rear derailleur. Apex is a more budget-friendly option, while GX is a mid-range groupset. The Apex groupset leverages the proven technology of GX Eagle AXS, offering a simplified, yet capable, 1x drivetrain experience.

IMO, GX is more equivalent to Rival...the Shimano MTB equivalant would be SLX. It gets kinda murky with XO1 and XX1 though. XX1 is marketed as being higher end than X01, but in reality it's more of the "XC" groupset. XO1 being the "trail" groupset. That being said, one of my gravel bikes is a mullet build. As delivered, Force AXS shifters and crank, paired to XO1 transmission. That same manufacturer specs the next lower bike with a Rival/GX combo.

One big pro for Microshift Advent X is the cassette is light if you go with the aluminum version, 425grams. Downside is it wears quicker. I'm on my 3rd chain and I think I'll need a new cassette when this chain is done. Pro the cassettes aren't expensive.