For me, merida was the nicest , and friendliest town in venezuela ( not a hard task i have to say) lots of students around so lots of bars and people that want to talk to you . Practise makes perfect. There are plenty of tourists , for venezuela anyway. and if you take a pocket full to dollars to use on the blackmarket it is cheap. you will cry if you try to live off travellers checks or cash machines. black market rate can be over 50% higher.
Venezuelans speak funny too ;o)
but the girls look good.
I am working in ecuador now. travelled here before. i think ( and i think the general concencus) is that the spanish in Ecuador is nice and clear and well paced, and teh folks are used to tourists trying their spanish in a heinz variety of accents. helps with confidence and getting understood. i have a slight northern english accent and can´t say RR for example. but it is tolerated here.
I didn´t quite get in to the swing of things in Cuenca. lovely looking place, with bike shops. but i felt it was a bit quiet,or you just had to know the right people.
All depends what you are looking for.
Colombia is definately some where you should dismiss either. i vote with Mr Ron.
But bear in mind if you start your trip there, you may ruin your plans and run out of time for the other places on the way ;o)