Please note that there’s no upgrade path from the plugins that are included with Cubase. They’re considered free bonuses for Cubase users and come with almost completely different content compared to the full versions. Only Padshop can be upgraded, and Retrologue 2 is already the full version.
I would recommend upgrading to at least Cubase Artist 9.5, which will include a ton of new plugins, such as:
-Retrologue 2, a very versatile virtual analog synthesizer. Great filters.
-Padshop, a very popular and highly regarded granular synthesizer
-Groove Agent SE 4, which resembles Groove Agent One but is much better. Includes over 100 new drum kits, plus a new deep sampled “Acoustic Agent” drum kit, which emulates a drum set recorded in a real room. Can load the new GA4 expansions such as the popular “Simon Phillips Studio Drums”.
-Halion Sonic SE 3, which includes an improved preset browser and many new presets not available in Cubase Elements.
-“Trip” expansion for Halion Sonic SE, including tons of modern, complex virtual analog synth sounds.
-“Flux” wavetable synthesizer for Halion Sonic SE, including many modern hard hitting presets great for dance music.
-Many new effects such as the pro-quality REVelation reverb, QuadraFuzz v2 and Magneto II for saturating and warming up your samples, and much more.
And of course, Cubase itself has improved greatly as a DAW since Cubase 7 was released. Almost everything people disliked about Cubase 7 and Cubase 7.5 has been improved, and many of the most popular feature requests have been implemented.
I think upgrading to Cubase Artist alone will keep you busy for a while, but if you need even more sounds, consider getting the full version of Halion Sonic 3 too at some point. The acoustic instruments are far better than the ones included with Cubase, and there are even more synth presets suitable for all kinds of music. It comes with over 3200 presets in total.