A normal hit, like a normal attack or magic, for me has to be 100%.
Anything less, it is reserved for risky attacks. Like, double attacks, but they are both weaker, like 3*atk instead of the usual 4*atk, and have only 80% hit chance. This way they are gambling for more damage in exchance for the chance of doing less or none at all, and makes sense since you need to sacrifice precision, both to hit and to hit right, to be fast enough to hit more. Triple, 2.5*atk and 70%. And one of 50% chance but almost guaranteed critical hit.
States like Blind making single-target attacks like main physical or single-target magical ones makes sense to me too. You can't aim properly what you can't see after all.
Stat-giving magics on the other hand... I'd only let them have a low damage chance if they are either cheap but powerful, like an instant-kill not that much more expensive than the basic fire spell but made about 30% chance, or give them secondary effects if that state chance didn't hit, like if they don't get the superpoison they still take the normal poison, some damage or both.
Now, for personal battler hit and evasion chance, be it actor, class or enemy... I like to keep the actor/enemy's hit chance on at least 100%, unless it is a very gimmicky one like the mentioned "extra effect when misses". Classes though, if you can change them they *may* increase or lower a bit.
Evasion is on a character basis, I guess. Some chance is good though, because while missing feels bad being able to avoid the hits yourself feels relieving.
I also don't like the normal hit/evasion calculations.
I think hit chance should also count some bonus when comparing the luck of both the attacker and defender, and evasion should be the same, but also include their agility in it.
I'd personaly use (hit calculation) * (1 + ((attacker's luk - defender's luck)/(attacker's luck + defender's luck)). That means the higher the difference in their luck, the higher an increase/decrease in hit chance.
And for evasion I'd add the agility in this, but more than luck, maybe double, (defender's evasion) * (1 + (((defender's agility*2 + defender's luk) - (attacker's agility*2 + attacker's luck))/(attacker's luck + attacker's agility*2 + defender's luck + defender's agility*2)).
Also, like yanfly did in his hit accuracy plugin, I think it is better to just combine the hit and evasion calculation. as in actual hit chance being hit chance - evasion chance. As it is it doesn't reward someone investing in equipment to raise hit chance over 100%, and a higher evasion will let you avoid the skill even if the hit chance would overshadow your evasion.
[Edit]
Just adding a couple boss ideas that could use hit and evasion in interesting ways... a boss that almost always misses at the point you'd fight it in a normal game, but at each miss grows angrier and stronger, only relaxing after hitting someone... and after the fifth miss you see the message "Nearsighter Berserker angrily cleans foggy glasses", fixing his miss rate to a normal one... only for next attack, hit or miss, to give the message "Nearsighter Berserker calms down, but glases are foggy again".
Or an enemy that starts with high evasion, but at every attack it evades you get the message "Deadly Dodger sacrifices a piece of armor to avoid damage", and indeed at each dodge defense lowers... until the message "Deadly Dodger sacrificed last piece of armor", kinda killing its increased evasion and damage resistance.
