What are some of the best expense tracker app? Also are there any expense tracking app for couples?

You can try Spendee, they have a shared wallets feature. Note that one of you will have to be on the Plus/Premium plan tho.

I am currently using the free version of Monny and I think it does its job enough. Not overcomplicated. I don't really want to link this to my bank as there are many transactions that are not normal spending e.g. you paying for the whole table then they pay you back their own portion, lending some money to people etc.

My only issue is that it doesn't have a cloud function. I have two phones so I can only access it on my main phone (as compared to my work phone) and also can't access it on computer. But it isn't much of a complain as I think it serves its function well enough.