I want to be logged in so I can do most things on Reddit like post and comment. I want it to be a web frontend rather than an app because I keep many tabs on Reddit open in my browser while doing research on things (like digital privacy for instance!). I did some searching and didn't find any currently working frontends with login support.
Very unlikely to exist. Libreddit (that didn't support user login to start with) was discontinued a while ago, and Reddit's hostile stance on 3rd party clients in general means any project gaining prominence will get killed before they become popular. RedReader (an Android app) is only permitted to use its API for free because of public outcry due to accessibility issues involving blind users. A web frontend with user login support for Reddit will get hunted down by Reddit's legal department if it ever reaches maturity.