Practical question: Why get a 3DS or Vita instead of a tablet?

[miz1q2w3e]

They're not the best browsing devices, I only use them if I'm feeling too lazy to get my laptop (3DS is wifi only btw)

Obviously, the main reason to get a 3DS or Vita is if they have a game that you really want to play and it can only be played on it. Unless there's a game (better if there's more than one) that you really want, I wouldn't buy a dedicated handheld if I were you, especially if you have limited funds and must choose.

There were a few games that I wanted on 3DS + a TON of DS games I couldn't play cuz mine broke = I decided to buy a 3DS instead of a new phone a couple of weeks ago. I don't use 3G/whatever for internet and I have a laptop so I didn't really care for a tablet either.

If the stuff you mentioned (internet, PDFs...etc) is important to you and you don't have any must have games in mind for 3DS/Vita then I say go for it and buy a tablet!