Honestly I'd recommend reading and understanding, because Ramadan is the month of Quran because of many verses such as in surat al-Baqrah or al-Qadr.
From the sunnah we learn that Jibreel (Peace be upon him) used to teach, study or revise the Quran with our Messenger (Peace be upon him) during Ramadan, so this is what we might have to do in first place. (see also this fatwa). And to study and teach the Quran you must understand it, that means reading in a language you understand.
On the other hand we can gain thawab (rewards) by reading the Arabic because of the well known hadith and this could also be concluded from this hadith, which shows that even a person who find it difficult to read would be rewarded.
So the best would be to find a good mix between both.
See also this fatwa on how (order) on should read the Quran.
Here two ahadith (without comment) on the importance of reading the Quran:
Abu Umamah (May Allah be pleased with him) reported:
I heard the Messenger of Allah (ﷺ) saying, "Read the Qur'an, for it will come as an intercessor for its reciters on the Day of Resurrection." Sahih Muslim
Narrated Abu Musa Al-Ash`ari:
Allah's Messenger (ﷺ) said,
"The example of a Believer who recites the Qur'an, is that of a citron which smells good and tastes good; And the example of a Believer who does not recite the Qur'an, is that of a date which has no smell but tastes sweet; and the example of a hypocrite who recites the Qur'an, is that of an aromatic plant which smells good but tastes bitter; and the example of a hypocrite who does not recite the Qur'an, is that of a colocynth plant which has no smell and is bitter in taste." Sahih al-Bukhari
And Allah knows best!