Either tassel loafers or penny loafers would go with anything from jeans up to wool slacks and a sportcoat. Very few people on this site would recommend wearing loafers with a suit, although some people wear tassel loafers with a suit to non-business occasions, such as dressy restaurants or outdoor weddings in the summer.
Tassel loafers are classic, but they are a bit of an "older" look than penny loafers. I'm an attorney, and a lot of lawyers in the senior/partner/supervisory ranks wear tassel loafers. I see penny loafers on younger men far more often. That shouldn't keep you from wearing tassels if you like them, but I think they read as a bit dressier. I think that wearing tassel loafers with jeans or loafers "dresses them up" a bit more than a penny loafer would. Compared to penny loafers, they might be slightly better for business casual offices, slightly more at home in nice hotels and restaurants. Double monk straps are very fashiony; they're a lot of look. Very stylish, but I think that might be a bit flashy for a routine day at the office -- they're more of a date night shoe.
If your priority is versatility, for example if you have a small shoe collection, stick to calfskin in brown or burgundy. Black looks great at night, but it sometimes looks out of place with jeans and khakis, and is a more formal color, and the combination of formal color and casual shoe style can make it difficult to wear. There's a place for black loafers, but I would suggest holding off until you have your other bases covered.
Tan or walnut-colored loafers have a bit of the opposite problem -- they are very casual. They look great with jeans and khakis, and they're a great color to wear without socks and maybe eve with shorts in the summer, but they usually look out of place with sportcoats and slacks, and seem incongruous in the winter.
Brown is the most versatile; there are virtually no occasions on which it is inappropriate, except very formal occasions, but you wouldn't wear loafers to those occasions anyway. Burgundy is essentially similar. Many people believe that burgundy looks far better on more expensive shoes, and particularly in shell cordovan, than it does in less expensive calfkin (whereas black is black). Oxblood, which is a little brighter than burgundy, is a bit flashier/more stylish, and a bit less formal.
If you already have a few pairs of brown shoes, I would try burgundy tassel or penny loafers, especially if you have some money to invest in a nice pair.
Oh of course, they all weren't even tassel loafers! But thanks for overview. I am 26, working in Big 4, but our dress code is quite relaxed, some of my colleagues are coming with blue jeans and t-shirts (it's IT department). Still I want to do better than that.
Now by versatile I mean, I want to use loafer with many different outfits - from business casual at work, to going with jeans to a date. The dark brown tassel loafter looks quite formal to me, i assume i wouln't be able to pull that off with light blue jeans? There also burgundi loafter, but not sure I really like burgundi, it feels like a really aggressive color.
I think yes haha! My perception changes really fast on what I like tbh. I couldn't stand boat shoes, and now I got Sperry top-siders and lovin' them.
That said, I still prefer other shoes to loafers. For example based on looks alone, I enjoy these shoes much more:
But I assume they are much less versatile, if I choose to wear them with jeans or more casual outfit.. But still, I am finally okay to buy loafers.