Hi Sarah, I temp and would recommend temping over OPKs as temping is the only method that will give you 100 per cent certainty that you ovulated and when. OPKs can show up positive but you may not ovulate. They can also show up negative but you may still be ovulating.
That being said many lovely ladies on here do just use OPKs so do what works for you. If you are just starting ttc then you could always use OPKs for the first few cycles and then add temoing into the mix if no BFP just so you can confirm O is actually happening.
Obviously temping is no good for telling you when to dtd as only shows O after it actually happens. But as long as you're DTD regularly you should be ok.
I find temping very easy, keep my thermometer by my bed and set my alarm for the same time every morning, but know others don't find it easy to remember.
To sum up: if you're only going to do one I would do temping, but doing both won't hurt and will help you. :)