Ixionn

I would for sure say the CPU is the biggest bottleneck here, those Phenom II chips are very dated and underpowered nowadays. Even an upgrade to 3rd or 4th gen Intel would likely give you a huge performance jump, if not Ryzen like you mentioned. I would keep the 970, at least until you see how it performs with the CPU upgrade, then make your decision. The 970 is still a respectable GPU nowadays, it's about on par if not better than a GTX 1050. If you were to upgrade the GPU I would look into a GTX 1070 or better. Also I don't know a huge amount about Ryzens, but I believe you will want faster than 2666Mhz Ram for it.

$1500 will be 2080ti, $1000 will be 2070S since 30 series will come this year, making the worse value 2080 and 2080S among 20 series less preferable.
 
This gives you a better experience with customer service (so different companies can't blame each other for issues, even though they usually don't) and can match styles in appearance, but the hardware is not designed to require matched brands.

From a technical standpoint I doubt it really makes a difference. If you want to have a nice aesthetic build having just one brand may help your parts match up better in that way, other than that I can't really see a reason to stick strictly with one brand, other than maybe having most of the parts in your system have their warranty through ASUS.

I've always been an EVGA guy myself, but generally I would go for whatever brand has the best price available at the time. The cards themselves are all generally the same Nvidia design so it shouldn't make a huge difference, if you have a 2080 Ti you have a 2080 Ti. Never really heard of any major issues with EVGA, Asus, MSI so I would just price around, the EVGA cards are some of the best looking in my opinion.

Am I all set? Not sure if I'm earning the points I should or not. I noticed I'm not on the leaderboard for the LTT team, maybe that's only people with a huge amount of points, crazy horsepower machines? I'm running two machines, my desktop with an i5-4690k, 16GB DDR3, GTX 1070 SC, then I have my laptop with an i7-10510U, 16GB DDR4, MX250. My desktop has been running for two weeks or so, my laptop has been running for a few days now. My room these machines are both running in is heating up like crazy, never knew how effective a PC can be as a spaceheater! Anyway I'm hoping I'm all good here, got my team set for LTT, passkey is set, and registered into the giveaway you guys are running too. I know I don't have a massive amount of computing power here but I hope I'm helping out, thanks all!
 
(view here is from my desktop just now, points earned should be for my user so both machines, my laptop displays the same points earned.)
 

I know I may be a bit old school but I am not a huge fan of the glass front cases that are popular right now. I've been looking for a decent quality case with 2 5.25 bays for awhile, having 3 would be ideal. I often burn and copy CDs for my grandparents and I rather keep my good LG drive then trade it for a cheap USB drive, which would also just end up costing more for a worse drive. I also have a 6-fan controller which I could get rid of, but I'd like to atleast have space for my SD card reader and DVD drive. Main things I need are good airflow and a case designed to be quiet. Not looking for crazy lighting or anything, just a simplistic case, without side window is preferred. Don't want to spend over 150 USD if possible. My system uses an ATX board (not Micro-ATX). Current case is the infamous bright orange Corsair Graphite 230T. If any more info is needed just ask. Thanks all.

Depending on what games I think a CPU/Motherboard upgrade is definitely what your next steps should be for performance. Intel 3rd gen was around 2012 or so, your 1070 is definitely the best performer in your system. I don't think the 1080 Ti would be worth it when you already have a 1070 with your 3rd gen i7. I have an i5-4690k with a 1070 SC right now and I definitely notice my CPU being the bottleneck with intensive games.