The LG G5 wasn't quite the success LG hoped it would be. The phone's modular functionality, the primary selling point, never really took off. It didn't help that the phone was fairly expensive when it launched, hovering around $600-700 in the United States. The T-Mobile G5 (H830T) is now just $224.99 on eBay, which is $30-80 off what other stores are charging for the unlocked US model.
If you need a refresher, the G5 has a Snapdragon 820 processor, a 5.3" 1440p IPS display, 32GB of storage, and 4GB of RAM. It also has a removable battery and supports microSD expansion. As mentioned above, this is the T-Mobile variant, but it will work on other GSM networks too (AT&T, MetroPCS, etc).
For the price, I would say the G5 is a good buy. This T-Mobile model is even supported by LineageOS, so if you want more recent software (it ships with Android 7.0), you can go that route.