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The easier, no doubt, a GP as it can be almost at ground level at base, or base no higher than 1/4L (less than 7m) above ground. If mounted on the ground it can have many buried radials, but will need many! If anything from 1m to 7m off the ground, 2, 3 or 4 radials will suffice, these will be around 7m long each, start with 7.5m and trim or fold back as necessary.

If you use only 1 radial, or 2 radials that aren't directly opposite each other, or 3 radials that aren't roughly evenly spaced such as 2 that are opposite and one that is between them, missing the fourth opposite, then in all these cases the radiation will skew toward the radial side. You can use this if you want to favour a certain direction, or it may be dictated by possibilities of location.

The GP is very effective, easy to set up and get to resonance, good low angle but also high angle radiation when at the height of less than 1/4 above ground, do NOT raise it higher than 6m off the ground or you'll LOSE the low angle radiation contrary to what one might expect.

But also do not discount an inverted L EFHW! Although its pattern can be less predictable, if this is an easy option it is worth trying too. Say you have the feedpoint with the 49:1 unun at the bottom end and it goes say 7m up and then 7m across (it can slope down if need be, or be level), you have thus an Inverted L and these can be very effective too!

However with your dipole at 7m you probably have an equivalent of that already, so if it was me I'd go for a high doublet at least 12m up for 30m and ideally higher, or an elevated GP, since a ground mounted ground radials GP is a lot of work and I doubt will produce any better result than an elevated one for most of our amateur situations.

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