That’s a question everyone will have their own opinion on, Bathmatters. My two-penn’orth, for what it’s worth:
There are three weekly thematic puzzles. EV, IQ (in the I on Saturday, available in the digital format), and the Listener. There is also the Magpie, published monthly and containing five word and one number puzzle. I mention the latter because it grades its puzzles for difficulty from A (entry level) to a very occasional E (extremely tough). In my view EV is the easiest in general, mainly A and B with a few C thrown in. The Inquisitor is tougher, averaging B with an occasional A and more C. The Listener is less tough than it used to be, probably nearer C than B, with a smattering of A and some D thrown in. An E might appear once a year. That’s only a broad generalisation. But in one Listener year, judged by my solving times, I would expect to see roughly 8 A, 14 B, 19 C, 6 D and 1 E. The other four are numericals. In any one week any one might be toughest, but it’s unlikely to be EV, in my view. It’s worth saying that many setters contribute to all of the publications.
As for satisfaction, I like a challenge, so I choose difficult puzzles every time. Others prefer puzzles they can solve unaided. “Quot homines, tot sententiae”. My old Latin master used to consider the use of a dictionary to be cheating, but times have changed.