A2000: SM2263 + 96L TLC (Micron), Gigabyte is E13T + Toshiba TLC. So the A2000 has DRAM and arguably better flash. The main difference with the A2000 is that it has a large, dynamic SLC cache, which is very flexible, but less consistent than what you'd likely find in the Gigabyte drive.
The A2000 is absolutely better, DRAM plus a controller known for the best consumer performance, I have it a category (or half-category) above the E13T drives like the Gigabyte on my SSD buying guides for a reason. Large, dynamic SLC can be finicky, on the other hand the E13T relies on HMB (using some system memory for DRAM caching) which is also less reliable in my opinion, so they're both budget-oriented options.
If they were the same price and I was buying one drive for primary, I would personally go with the A2000, if those are you only two options.