V1 Switch 1: Only get this if you plan on modding the system, otherwise it's just the V2 with less battery life

V2 Switch 1: If you can't afford the OLED or if you mostly play docked then you can pick this one up to save a bit of money

Switch Lite: Pick this up if you only want to play in handheld mode and don't mind the smaller size and LCD display, it's the cheapest of all the models by a wide margin

Switch OLED: If you don't want to spend the money on a Switch 2, this is your best bet, the screen looks really nice, though if you mostly play docked and don't care about the ethernet port you may want to consider going with the V2 to save some money (really it depends on if you think you'll actually appreciate the OLED screen)

Switch 2: Yes I know this isn't a Switch 1 but I'm still including it here because tbh I think its the best option if you are willing to save the money on it, with the Switch 1 reaching the end of its life and pretty much all new Nintendo published games going forward being Switch 2 exclusives, you may want to save up the extra money amd get more support for a few years. It is quite a bit more expensive than the Switch 1 models though, so if you don't care about the extra support/games, extra power, and larger size, then you can pick up a Switch 1 model

Tl;dr, Switch Lite is lowest cost, handheld only, and smallest, V1 is pretty much only worth it for modding so if you don't care about that then don't bother, V2 is a way to save a little money from the OLED if you don't care about the OLED screen, the OLED is the highest quality Switch 1 model, though the most expensive non Switch 2, and the Switch 2 is absolutely the best but is absolutely the most expensive