Is it a good idea to buy some crypto for long time investment plan from exchanges such as binance as keep it there, any alternatives ? Because i have heard bad things about some famous exchanges such coinbase.
Are you referring to staking plans or something else?
If it's just staking I highly recommend you to just keep those assets in your personal wallet and stake them there, and as I know there are many proof-of-stake coins that you can hold in their supported wallet and your rewards will be assigned to you on that wallet and the reward should be the same as what exchanges are offering.
Specially if you're going to hold an asset for a long time exchange's 3rd-party wallets are not best place to keep them since they are mainly the target of most online threats in crypto, it's true that Coinbase and Binance till now proved to be really safe but who knows about what future brings really?