Underrated Openings? Anyone? (Preferably not gambits, but I could care less)

English opening.

Tarrasch 1. d4 d5 2. c4 e6 3. Nc3 c5

A very underrated and hated indeed opening is saragossa opening which is like the caro kann defence for white. It is very flexible so I don't know the reason for hate

Sorry for my English 😭

The reason Black plays 1.e4 c6 (the Caro-Kann) is following with ...d5 and taking back with the pawn if white captures on d5.

The reason White plays 1.c3 is that he is a beginner who has not realized that he can start with 1.d4 and follow with c2-c3 whenever (if ever) needed.

for white ,

bishops opening and g3 vienna in the king's pawn game. Theoretically equal but have a lot of poison.

torre attack drips with poison and is really only equal at worst. so many ways to get knocked out playing naturally
the traditional reti with 3.g3 (as opposed to now popuar 3.b4) has suffered a bit of a downturn in reputation but the extra tempo lets white get away with some interesting creative stuff that would be too slow to work in benoni's

1.b4 is still underestimated, esp by a lot of people that still buy into the old bxb4 with advantage argument when they havent looked at the new lines
1.g3 too is underestimated because people really do think you have nothing better to do than to transpose.

with black, there is a bunch of stuff in the ruy lopez as black that is very interesting and have their charm but between the berlin and petroffs dont get played a lot like like modern steinitz and the cozio (although the latter has been making a comeback). rarer stuff may be viable too but would require more thorough work.

old indian is quite underated in the engine age, because of superficially high evals (for example one of the most critical lines in it reaches an endgame thats a 4 vs 3 pawn bishop endgame thats known to be a draw with best play)

hanham philidor has pretty much earned its respect already, but the exchange /antoshin philidor is still underestimated. Plenty of material analyzing some lines till like move 30 that show it is ok if you want to make it work.

i think the early nc6 french (3.nc3 nc6) is quite decent yet almost no one seems to know it.

O'kelly sicilian is very easy to underestimate. 
lines like the taimanov and the zurich in the nimzo indian suffer from the same "problem" all those interesting responses to the ruy lopez suffer from, they are ignored quite often not because they are bad but because other more mainstream lines have a better eval score.

i can go on, just off the top of my head.

Honestly, i would def try the Nilson Gambit(or it might be known as the Garrett opening i think? something like that) its newly discovered and you can checkmate in less than 10 moves. i would definitely look into that, it might help! maybe you've heard of it before 😉

Budapest Gambit is underrated as anything

Also the Ware Opening/Defense, Pawns only openings, and Wayward Queen Attack have high win rates for being so unprincipled.