Whichever you choose, you'll want the other. So, it may be a question of order of acquisition. In which case, for most, it's pad then goggles.
My preference is the goggles because the experience is like no other. However, at times, they can be impractical, but that's only because of other people. If you are flying without others being nearby, which may simply be time of day, or within your car/truck, then goggles are the way to go.
You will NEVER have difficulty seeing the screen with goggles; regardless of how sunny it is, and your ability to judge distance from objects is greatly improved. With goggles, you can confidently thread the needle, so to speak.
The battery in the goggles lasts for six hours without getting hot. I don't believe that's true for any other device, not even crystalsky. I have the crystalsky.
The goggles take some getting used to, but it's not rocket science, and you can get familiar and learn to use them without flying the drone, just take off the props, turn it on, and learn the goggles from within the comfort of your home. When you are ready, go fly. I ALWAYS take off and land without the goggles, but once it's all systems go...it's goggle time.
The goggles do display drone battery life remaining. You have to remember what percentage your low battery warning is at...20,25, 30 whatever. Besides, you have to use a phone, or tablet to fly with goggles these days. That was not always the case. So, if you are concerned about RTH battery life, lift the goggles, and look at the phone/tablet screen to check.
With the ipad, you will have difficulty seeing the screen. There are only two styles of sun hood that can help. One is the tube like Hoodman, and the other you have to make yourself, and that is a sunhood that has a back wall at less than 90 degrees. I don't know why this style is not commercially produced.
If you go with a large ipad, consider hooking it up to a tripod to alleviate the weight, and have it at eye level. I do that with my Crystalsky. People think I'm on a professional photo shoot.
When you fly using the goggles, the rest of the world just disappears. The immersive experience is remarkable, and cannot be imitated by phone/tablet, not even approximately.
If one day, you decide to get the goggles, don't bother with the other sets...Litchi app, fatshark, moverio, etc...I have had, or studied on the differences of each, and the DJI goggles win hands down.
The DJI goggles LOOK RIDICULOUS, but they are AWESOME!!!
BTW...I disagree with the statement that flying while using the goggles is a guaranteed crash. The risk is no more or less than with a phone/table as FPV. Regardless of the monitor, we have to be careful. We are dealing with a fragile expensive flying camera, which 'sounds' really weird.