Both methods can yield excellent results if done right. But both need some amount of practice for that. One disadvantage of toner transfer is that it's difficult to make just a small board - meaning you'll end up wasting the rest of the letter-sized transfer paper, which makes it a bit expensive. On the other hand, photo-resist board material is more expensive by itself and needs more care with handling (no exposure to light). No matter which method you chose, I'd suggest doing a few trial boards as an exercise before you launch into anything complex.
Don'f forget there will be some significant startup expenses - exposure box (for photo-resist) or transfer paper (for toner transfer), raw copper-clad board material, etching tank, etching solution, brushes etc. (to clean the boards before and after etching), drill stand and drills. To get decent results you'll need decent quality equipment, and that does not come for free. In addition, those etching chemicals need to be replaced after a few uses and are
highly toxic (and also stain your clothes), so don't do it ANYWHERE near food, assure good ventilation, use rubber gloves and protective goggles etc., thoroughly wash your hands after etching. And by all means keep the equipment away from children. And don't spill it into the sink, instead bring it to a recycling station.
If you only need to do a few boards overall, you may want to look into having them made professionally. No nasty chemicals, no time spent on drilling dozens or hundreds of holes, no wasted boards etc. I did a few boards myself (toner transfer) but in the end decided it wasn't worth the time and effort compared to just ordering them from a low-cost vendor. ExpressPCB offers 3 boards for around US$60 including shipping (but you need to use their design software). PCBCart accepts standard Gerber files and is cheaper for larger quantities and more advanced options (silkscreening, multi-layer boards, Gold plating instead of solder reflow). The cheapest for hobby boards I've found so far is
www.platinenbelichter.de (they also ship internationally for very reasonable cost, just ask), their capabilities are similar to a hobbyist (meaning, no special plating, no silkscreens, no through-plated vias) - etched and drilled boards, for a very low price, and you can just send them a picture (e.g. PDF) of your board layout instead of Gerbers.