OP, I'm not surprised you are having a hard time. Can I suggest you need two tents and just accept that's the cost of enjoying the outdoors. But if you buy right the first time it will easily last 10 years.
If you have not been pinned down for a few days in fowl weather than you may not fully understand or appreciate the situation. Forget about some super light mesh summer tent. When it's cold, wet, blowing hard, you are days from help, and your life may depend on it you WANT a heavier sturdy 4 season tent. The super light advocates will say no need, but you don't find many of them comfortable and smiling when the weather has gone pear shaped. I doubt any summer tent will hold snow.
Keeping fowl weather in mind two entry points are welcomed, one for each user and gear preferably, or one for gear if smaller and access elsewhere. You also need the space to cook in it as well. Single skin V multi pitch, free standing V pegged, silicon V poly all have advantages and disadvantages. I prefer multi free standing. Good for pitching on slab, dry inner - always, and can take the top off if it's hotter than expected. Weight is also a priority, and always a tuff deal breaker as you carry it for as long as you sleep in it.
Many decent bands have been mentioned already on here. Perhaps look at GoLlite teepee tent which is a good compromise of the above. They were having management issues I believe, not sure if they are around anymore unfortunately.
Summer: just go a plastic sheet, thermarest, and enjoy the stars. Of if you must some super light mesh thing or a fly.