Old Town vs Dagger

I am about to purchase my first kayak, I have it narrowed down to Old Town Heron XT 9’ or a Dagger Eclypse 11’

I think these are correct names, either of these be a good platform for a beginner

Except for white water
Longer is better. Somewhere about 14 feet long you will be able to keep up with most other paddlers. Somewhere past 18 feet long the top end speed keeps increasing but it takes more work to go the standard cruising speed of 3.5 to 4.5 mph that most folks paddle in groups.

how do you plan to use it?
Could be decent choices, but very much depends on how you plan to use them. And also whether they fit you.

If you plan to do any paddling besides floating around on a small lake/lazy river, the Dagger will probably be better. It is longer, so it will go faster and track better, making it better for going on short trips. I am sure the Heron is stable and durable, but it will not be as fast as the Dagger.

Second the question of intended use
These are rec boats, meant to float around on calm water and not do fancy stuff like WW or make things like rolling easy. If the former is your goal, no problem. If you want to do the latter, you need to learn more about kayaks and paddling environments to make a good first choice.

Have you looked at used?
Craigslist can be a good source of used kayaks as long as you do your research to make sure the asking price is reasonable. If you buy used you will have a fair chance of recovering your investment if you change your mind. You might also find the local kayak club and see what they might allow you to try out before buying.