I have certs from TDI and IANTD. I prefer IANTD because it is more available here. But TDI is more available in other countries.
Both organisations are ok, they teach all you want, oc, ccr, cave. I prefer them over 'DIR-organisations', because your courses will not be with a 'single-one-way, this-is-best'-view. I have no DIR-certs, but I was DIR-minded in the beginning of my techdiving. I still use things from that time like ratio deco if needed, or do stage-rotations instead of left-right carrying cylinders. But I can do both and that gives you more freedom in diving. My oc-configuration is like gue-divers, lights and so on same places. But I have done dives that are not possible with standardgases because longer deco and more gas needed. Teamdiving is ok, but you need to be self-sufficient/reliant in techdiving and that is a point you will not learn in my eyes well enough if you only look at DIR. Further I don't like the 'we are the best'-thinking of some DIR-divers (not all divers are so). There is no 'we are the best' in diving. TDI and IANTD will teach you what you need to know and how to make the dives you want to do as safe as possible. I turned over from oc to the 'darkside' too. That is possible with TDI and IANTD too, they offer oc and cc courses.
So look around for a good instructor, talk to him, tell your plans for future if you already know them. A good instructor will have a lot of experience in the dives he teaches, can explain things to 'noobs', takes time to explain and will learn you the new things quiet and as safe as possible.
Both organisations are ok, they teach all you want, oc, ccr, cave. I prefer them over 'DIR-organisations', because your courses will not be with a 'single-one-way, this-is-best'-view. I have no DIR-certs, but I was DIR-minded in the beginning of my techdiving. I still use things from that time like ratio deco if needed, or do stage-rotations instead of left-right carrying cylinders. But I can do both and that gives you more freedom in diving. My oc-configuration is like gue-divers, lights and so on same places. But I have done dives that are not possible with standardgases because longer deco and more gas needed. Teamdiving is ok, but you need to be self-sufficient/reliant in techdiving and that is a point you will not learn in my eyes well enough if you only look at DIR. Further I don't like the 'we are the best'-thinking of some DIR-divers (not all divers are so). There is no 'we are the best' in diving. TDI and IANTD will teach you what you need to know and how to make the dives you want to do as safe as possible. I turned over from oc to the 'darkside' too. That is possible with TDI and IANTD too, they offer oc and cc courses.
So look around for a good instructor, talk to him, tell your plans for future if you already know them. A good instructor will have a lot of experience in the dives he teaches, can explain things to 'noobs', takes time to explain and will learn you the new things quiet and as safe as possible.