Uniswap is a Dex exchange and polkadot is not, they aren't on same level as polkadot have a higher chance of surviving in the future, remember there are few Dex exchange in the past that aren't no more so nothing is certain here, it's left for the team to keep doing their best but as for me I'd go with polkadot any day
technicall they were not same technology , polkadot was a smart contract platform like ethereum bsc matic and many others. both polkadot or uniswap due ecosystem growth the utility and usage also increased massively , and it have positive effect to its price. in future while crypto market recovered, i am believe it could hit new all time high and even break it .