There's plenty of cars that go over 200MPH now, but on what roads are you going to do that on a regular basis?
Maximum theoretical sequential read/write is great for daily transfers of large chunks of data, or for bragging rights, but most of us here won't ever use that speed. There's a few things to look at:
1) Random I/O speed: This is going to be more related to real world performance, so you'll want to check specs and reviews. Depending on the drive, a PCI 3.0 could be much faster than a 4.0 in this area.
2) Longevity: How many total writes can it take before the drive may die. Usually measured in TBW. You'll find some large Intel (or others) SSDs selling quite cheaply. It's because they use a different type of NAND that is not designed to allow as many writes. The theory is the average desktop user is not adding and deleting gigabytes of files on a daily basis, so this might be totally fine for some. But bigger doesn't always mean better. If you're a power tech user, you'll want something with a higher TBW rating so it will last.
There's other stuff to think about like Provisioning, but that's another topic. Quick rule is if you don't know how your drive handles provisioning, try and get a bigger size drive and plan to keep 10 to 20% of the drive free at all times.
For the average gamer here, top speed is not what they're looking for. A good quality drive, with a good TBW rating, and good IO performance, then get the largest size that your budget allows.