It really depends on what kind of game you're looking for. There are a lot of very good single player games out there, and what's right for one person might not be right for another.

Here are some questions you should keep in mind for selecting a game (besides budget): Are you looking for something lightweight that doesn't take up a ton of room and can be played quickly? (Friday, Onirim)

Are you looking for something heavy where you have to spend time thinking about each action? (Mage Knight, Spirit Island)

Is this a game that will be sitting out on your table for weeks? (any campaign game)

Are you looking for something with a story/adventure? (Tainted Grail, 7th Continent, a lot of other Kickstarter games)

Do you want something that has a ton of expansions coming out all the time? (Arkham Horror LCG)

What genres are you into (sci-fi, grimdark fantasy, historical, etc...)?

As mentioned in another comment, the People's Choice top 200 by the BGG 1 Player Guild is a very good resource, but I wouldn't necessarily focus on just the top 10 (for example, I'm not a fan of Spirit Island or Marvel Champions, but I know other people are).

Here are the games from my collection that see the most repeat solo play.

ROVE

Navigating the chain of spatial puzzles is just thinky enough to not outlast the games short length.

I play all mission expansions mixed together, sometimes crawler, sometimes reconfigured. A normal game of completing seven missions takes around 10-15 minutes once you know how to play. The longer game of play until you lose can last a fair bit longer.

SpaceShipped

You are trying to outmaneuver an automa opponent to be the first to obtain two rare resources in a fluctuation market.

I like the Infinite variant you can find on bgg. Games tend to run half an hour for me.

A Feast for Odin

You alternate taking turns in worker placement in an elegant solo mode. Trying to maximize the polyonimo space you can cover with minimal actions is always fresh and fun. Runs near two hours for when I want a longer session, or a game over the course of a week.

The base game is good. The recent reprint comes with two great expansions. Norwegians completely reshapes the game into something even better if you liked the base game and want to give it more life.

Great Western Trail(s)

Build up a new each game loop of action spaces to try and maximize VP by selling cows, moving trains, and building more actions. I tend take 2 hours for a solo play.

I own both the first game and Argentina. For solo I slightly prefer Argentina, but they are tied for my favorite game on the shelf. The series is great enough that I have New Zealand preordered.

Here’s 200 to consider!

2022 People's Choice Top 200 Solo Games (1-200)

I really love Spirit Island. It has a ton of expansions and there are a lot of additional rules to add difficulty and complexity to your liking. It’s also great to play with others too. A 10/10 game for me. It’s basically the opposite of Risk. People are trying to colonize you island. You play as a spirit of the island (river, volcano, storms, ocean, etc) and instill enough fear/kill them to get them to leave.

My favourite is final girl, the horror/slasher theme really fits the luck of a dice game, i think it is one of the most immersive board games ever. Another good, albeit completely different game, is resist, which is a game about the spanish resistance trying to intervene with military operations

Eldritch / Arkham horror.

I think Cartographers have a single mode, never tried tho.

• terraforming mars
• mage knight
• nemesis

SpaceShipped, Marvel Champions, Arkham Horror, Hero Realms, Onirim. I also really enjoy this geeklist (not mine) Modern Solitaire/Solo Games Using ONLY a 52-card standard deck. Regicide, Scoundrel, and Card Capture were my favorites but lots of great games on there.

Friday is a great little card game that plays fairly quick and can get tossed in a backpack easily.

I only ever tried Everdell SP and it works surprisingly well. Yeah its a bit different to the normal gamemode but I even prefer the different strategies you have to follow

Spirit Island, best single player game ever created.