Generally speaking a good saddle manufacturer does not make uncomfortable seats, but a less than good bike with parts fitted that are at the budget end of the market will be very uncomfortable.
If you really want a good comfortable saddle, get the bike set up correctly and fit a Brooks saddle. It will take some time to bed in the saddle, but during this time it will be no more uncomfortable than the seat you already have. Once it is bedded in you will want to keep the saddle forever.
Remember to follow the instruction you get with the saddle.
There is a huge range of Brooks saddles from minimalistic racing styles through to the plush fully sprung off road styles. They are not cheap, but are worth every penny.
