Mario and Luigi hands down. Mario and Luigi had two spectacular entries (1&3), a great entry (4), and a decent entry (2). Paper Mario had one spectacular (TTYD), one great entry (PM64), one decent entry (SPM), and one entry I actually REGRET playing (Sticker Star).

Paper Mario(SPM excluded)

Both are great though.

Paper Mario sticker star.

dont read the hate.

Paper Mario!

Mario & Luigi! I am playing Paper Mario Sticker Star right now and I'm enjoying it a lot, but M&L is amazing, Luigi really shines! Both series are awesome! I'd love to see a fusion of both, a Paper Mario $ Paper Luigi: Super Star Year door or something like this hehe ^^

Fuse SMRPG with it:

Super Paper Mario & Super Paper Luigi RPG: The Legend of the 7 Super Stickers Thousand Year Door Star! Inside Bowser Partners Dream Time Team!!

Would be a hit in Japan.

I actually think SPM is spectacular as well, it has the best story out of not just the Mario RPGs, but of the entire Mario series.

Disagree. SPM had an okay story, but it was NOTHING on PM:TTYD story. Just because you're saving the multiverse instead of the world doesn't make it automatically better. TTYD has better characters, better humor, and better writing in general. SPM isn't terrible, but to me the writing was the second worst of the Mario RPGs. Still not terrible, but a poor excuse for an RPG story. Nowhere near as bad as Sticker Star. Sticker Star was so horrendous I've seen Mario platformers with better story. Of course, Sticker Star was barely an RPG at all, but whatever.

While Mario and Luigi have considerably hold up much better than the Paper franchise, and Superstar Saga is still a superb game even by today's standards, I can't simply overlook Paper Mario: The Thousand-Year Door. It is so dark and bizarre, I just love it. So Paper Mario franchise for me.

Paper Mario is my favorite Mario series bar none,
However, if we're comparing series, then Mario and Luigi is better, despite never having played it I've heard good things about it from my friends.
SPS is ok, but in my book its not true the series, another standard 2,5 3D mario game dressed in a Paper Mario skin, and Sticker Star which is a bastardization(imo)

Paper Mario was creative and truly innovative, and TTYD was the epitome of a wellbred sequel, improving the gameplay significantly and expanding the scope of it. SPM and Sticker Star simply abandoned the formula, and I would appreciate them more as spinoffs rather than the following iterations.