What area are you from? I have never seen or heard of a big box store selling 2× poplar. I am also surprised to hear that the poplar 2×s are cheaper than pine. For hobbyist woodworking I think poplar is preferable to pine everyday.
I think it depends on what you want whether poplar or pine are better, tbh. Poplar's very stable, it's great if you want to paint it, and it does take some machining (chiefly routing) a little nicer, but I personally really like the grain of pines and firs quite a lot compared to the weird greens/purples of conventionally available poplars.
Both are soft enough that you can't really beat them up.
So I mean, I'm from New England, and maybe this is just a cultural thing, but I think that well-treated pine looks really nice - a golden hue from an oil-based finish, plus pretty brown knots. I don't love the table design here, live edge isn't my thing, but this wood looks great to me: https://cswoods.com/products/eastern-white-pine-dining-table...
But you can get nice grain out of other softwoods, too. Because it's very easy to get hold of here, I use white fir sometimes in furniture. Not "fine" furniture, but simple house stuff. This tabletop was actually the first thing I ever did in my shop and while it hasn't held up amazingly (my breadboards popped and I haven't fixed them yet) I quite like it for what it is as a learner messing around, more or less, and the sap intrusion along the breadboard still makes me happy when I see it: https://i.imgur.com/nipUhLs.jpg
