Yo Josske!
The AKG C214 is a cardioid only mic based on the C414 capsule. While it is true that the C414 is often used as an instrument mic, there are many vocalists who use it with great success, such as Celine Dion.
What you have really asked is more difficult, though. Imagine that you asked, "I already have a Honda Civic, but I think I think I'm going to buy another car, say about 10,000 pounds. I'm going to use it for driving around, mostly me, but sometimes I might let my girlfriend drive it. What do you think of the Toyota Corolla, or Volkswagon Golf?"
When placed in that context, do you see how essentially unanswerable the question is?
You currently have a fairly well made, inexpensive Australian capacitor mic. So you are looking for another inexpensive capacitor mic, primarily for vocals, and your budget is a little higher than it was for the first one. My assumption is that either you are looking for a mic that is better, or one that is different than what you have. And because you have listed prices in pounds sterling, I presume that you are in the UK. This affects your decisions, because tariff situations make USA made mics somewhat dear, from your perspective.
From here on, everything I say is just opinion, not fact. The C414 is a mic that is *better* than the NT1a, but not particularly *different*. The ADK mics are not any *better* than NT1a, but may be *different*. My best advice, if you are looking for something better, but not really different, in that sense, is to look for a used C414 rather than a new C214. Where we are (the USA), a used C414 in good condition isn't much more than a new 214, and the 214 is too new for many used ones to be available. If you are looking for something different, I would consider a high end dynamic mic, such as Shure SM7b. Used sucessfully for both live and recorded vocals, it is often the mic that works when a capacitor mic doesn't. It should fall into your price range new. Best of luck.-Richie