Samsung 990 EVO SSD is a great choice.

For under $250, you can get the SAMSUNG 990 PRO Series

1. Samsung 980 Pro SSD

• Fast PCIe 4.0 NVMe SSD
• Read speeds up to 7,000 MB/s
• Perfect for gaming and creative workloads
• Available in 500GB, 1TB, 2TB capacities

2. WD Black SN850 SSD

• Also a fast PCIe 4.0 drive
• Read speeds up to 7,000 MB/s
• Great performance for high bit-rate games
• Comes in 500GB, 1TB, 2TB

3. SK hynix Platinum P41

• PCIe 4.0 with read speed up to 7,000 MB/s
• Low power consumption benefits laptops
• Advanced thermal control
• Available in 1TB and 2TB

4. Crucial P5 Plus

• Affordable PCIe 4 option
• Sequential reads up to 6,600 MB/s
• DRAM and Micron 3D NAND technology
• Capacities from 500GB to 2TB

The Alienware m16 supports PCIe 4.0 so I'd recommend going with one of the first three options to take full advantage of that extra bandwidth. The Samsung 980 Pro or WD Black SN850 would be my top picks for the best combination of cutting edge performance and reliability. Make sure to get 1TB or larger to have room for several games.

Don't forget to check what's already installed in your Alienware m16. Dell often uses high-quality SSDs from the factory. If you're just looking to expand storage, you might consider adding a second SSD rather than replacing the existing one. The laptop should have two M.2 slots available.

Both Samsung and WD SSDs are great choice.

I also recommend the Samsung 990 EVO SSD.

Crucial P3 Plus

SN850X: https://www.amazon.com/WD_BLACK-SN850X-Internal-Gaming-Solid/dp/B0B7CKVCCV/?tag=6890-20