cyclezen

Welcome Laura,
It's great that you have done some extensive searching and getting info to make your decisions. And your 'problem' is just a matter of the way things are. Higher cost, more cooler stuff.
So I think you can make your decision, if you prioritize what all you think you want and then set the limit - of money or stuff.
Maybe I can help with the prioritization. By going thru your list with you. I did look at one Bike you listed - Marin Bobcat, and it comes in a number of different flavors with different features - 2 which seemed to fit in your parameters were Bobcat Trail 4 & 5, so lets use those for comparison. I'll assume you're athletic and with mulit-talents as comes to sport/outdoor activities, but also lighter smaller at 125 lbs. 5'2"
1. Tapered headset (tube) - Unless you're a real experienced, hard driving and/or very big guy, I doubt you would be able to tell any difference between tapered and non. It takes some real hard riding, over some serious tough terrain and much abuse for any difference to be noted. So, in your case, I wouldn;t even be thinking about this. Only caveat is upgrading to some very highend Sus fork which comes only tapered. But then this level of bike is not what I'd put a $1000 fork on...
2. Dropper seatpost - a very nice OPTION, which I don;t think you could get on anything less than $1500, so most likely a worthwhile upgrade to most any mtb. down the line...
3. Color - maybe not as important as some of the other stuff, later in the list.
4. Internal Cable routing - like you said, nice but not necessary - but very nice if you can get it.
Now we get to the important stuff
5. Tubeless Compatible Wheels (don;t expect tubeless tires until you buy bike as 'tubeless'), nice, but most bikes in this category may not have 'tubeless compatible wheels'. BUT most all the wheels on Branded Bikes are capable to be converted to tubeless, with a quite inexpensive kit, then you'll need tubeless tires.
6.Thru Axle would be nice, certainly, and could be one place to decide between bikes. Thru axle allows for certain upgrades not available to Quick Release - BUT, is a bike at this level worth a bunch of 'upgrades' or is it better to sell and buy something with more stuff - later? some of these level bikes have nice frames and generally good stuff, worth upgrading IF one wants to do it over time, a little bit at a time.
7.Hydraulic Brakes - always a nice thing. I have both hydraulic and Mechanical. I like both, but Hydraulic does have better stopping power. Athough I've never gotten to the point of max-ing out either, or needing to... And some hydraulics are better than others. I would ask questions for comparison and then decide if that step up is important for you.
8. 1x Drivetrain - a very nice thing for mtb and I think a very worthwhile feature to have. COmparo of the Bobcat Trail 4 with Advent 1x9 drivetrain to Bobcat Trail 5 with Shimano 1x11 - The Adevnt is a nice system, works well, durable, allround good. But the Shimano is 1x11, and often those extra gears in a range make riding just a bit more predictable and easier. and 1x11 will likely be more enjoyable as you improve and use your gearing better. $200 differnce between models - and there are more upgrades between the 2 - like the fork.
9. Fork - certainly a good fork makes a huge difference not only in comfort but very much in how well you're able to ride through more difficult terrain. So a really better fork is a great reason to step to a higher model. The Bobcat 4 has a SR Suntour XCM HLO-DS, 120mm Travel, Hydraulic Lockout, - all good things. The Bobcat 5 has a SR Suntour XCR LOR-DS, Thru-Axle, 120mm Travel, Hydraulic Lockout, Damping Adjustment - so more adjustments possible, and is front ThruAxle
But both frames seem to be 135mm rear, which could also be Quick Release rear - an older rear width, which might not allow further upgrades. But again, are you thinking of a Bike to hold for a long time and wanting all upgrades ? Then Full Thru Axle and Boost 110 Front and at least 142mm rear is what you'll want - But that's gonna be a lot more money up front, quite a bit more...
Frame - most bikes like these Marin have frames which easily could be used for more expensive models, they have modern geometry, light and well design and built bikes.
Bike sizing is important and because of that geometry becomes important. There are reviews on most of the bikes you mentioned, and reading them might give you comparisons.
SO
Good fork, a good 1x Drivetrain, Hydraulic Brakes - in a bike which fits you size-wise.
then consider the other stuff. including things like saddle, bars, color...
ANd, of course, is the bike, in the size you need, available? That's been an issue these past 2 years...
Good luck, Keep us updated on your progress. We always love to hear how things turnout.
Ride On Yuri
EDIT: I didn;t touch on wheel size... Best is to ride both sizes and see what you think. I recently bought a 29r, rode a bit, but never got real comfortable with it.
Felt too big and more difficult to maneuver through many tight sections of the terrain I get to ride in my area. I tried 27.5 and felt it was way better for me. Bought the 27.5, sold the 29r.
I'm 5' 9.5" , now only 142 lbs, definitely not hard charger (to my mind), but not timid or easy going rider either - I do like the tech riding... although breezing down a 'trail' is fun, I'm not gonna launch any big air - too old and break easily theses days... LOL!