I have always made this decision completely based on what each individual bird likes, because they all are very different in what they like as far as a bath, a shower, misting from a bottle, etc. Some birds HATE water and want nothing to do with it no matter where it comes from, and others absolutely love it and would do it multiple times a day if you let them (not advised)...
I have a PVC folding shower-perch attached to my shower wall, and whenever I take a shower they all have the option to come in with me; I fold out the shower-perch, get in the shower but leave the bathroom door open, and the 4 of them always come in to the bathroom and sit on the shower-rod, but each day is different as to who gets in the shower with me...Bowie, my GCC, usually takes a shower every day, and Lita, my Quaker Parrot also typically gets in with Bowie. Kane usually waits until Bowie and Lita are done and go back up onto the shower-rod, and then he jumps onto the shower-perch, and sometimes he just sits there and doesn't really get wet, and sometimes he does (I have the shower-perch attached to the shower wall with the suction-cups that are on the back of the perch, and it's located so that the end of the perch is in the shower stream but so the other end of the perch is out of the shower stream, so they can go in and out of the water)...And Duff, my Cockatiel, just recently started taking showers/baths about a month or so ago, she used to HATE getting wet and would get really, really angry and become enraged if she got wet, lol...But since Duff regained her ability to fly again, after not be able to fly since the age of about 10 months-old due to a wing injury (she's now 3 years-old), she has gone from being a complete introvert who was always quiet and rarely made a peep, never played with toys, basically just sat on my shoulder or on top of her cage and was a sweet little girl...NOW DUFF IS SASSY!!!! No joke, she has become a completely different bird since she started flying again, little by little she started becoming more and more vocal, started flying all over the house, started shredding the hell out of her toys, she now demands preening from Bowie and if he doesn't do it immediately as soon as she lowers her head for him, she starts beating him up and kicking his butt, she does the same to me, lands on my shoulder and lowers her head, and if I don't immediately start giving her scritches she full-on attacks my ear and the side of my head, and while she used to be scared to death of Lita and would run away from her as soon as she saw her enter the room, she now starts violently screaming at her as soon as she sees her, and then she goes after her and chases her away!!! She's also gained a noticeable amount of weight (she looks so much better, she was a frail, fragile looking thing), and her feathers are just absolutely GORGEOUS now, when prior they were always ratty and just a mess, and had no sheen to them at all...She's a totally different Cockatiel now, except that she's still the sweetest bird in the entire world to all people...But otherwise SHE'S SASSY!!!
Anyway, I wouldn't even force your bird to take a bath in the sink, although it is hard to tell whether or not they are enjoying it or they hate it sometimes, especially if they don't fight to get away and out of the water right away. You don't want to push them, but bathing is good for their feathers, their skin, and just for their hygiene in-general as long as it's not more than once a day at the most so you don't dry their skin out...Sometimes if I shower at the gym or at my mom's house, or wherever else but not at home, I'll put a little shallow container of warm water out and Bowie, Lita, and Duff will all hit it up, Kane HATES baths, he only showers...
So it's just about trying different ways of bathing them and just seeing what they like...Some prefer a shower, some a bath, and others that don't like bathing at all will usually appreciate a good misting with a squirt-bottle if you spray it up in the air above them and let the water fall over them...Then they'll preen themselves and fix their feathers...And especially if you have a "dusty" or "powdery" bird, like a Cockatiel, a Cockatoo, or as I'm finding out a Pigeon/Dove (dust EVERYWHERE)...
The PVC shower-perches are pretty cool, they stick to the shower-wall with 3 suction-cups that are attached and they fold flat against the wall when not being used. You can easily make one or buy one online for like $15-$20.